Patent GB-827164-A (GB)
Title: Improvements relating to digital data processing apparatus
IPC: G06F17/30
Filed: 1956-08-24
Abstract: 827,164. Electric digital-data-storage apparatus. DIRKS, G. Nov. 25, 1957 [Aug. 24, 1956 (2)], Nos. 25886/56 and 25890/56. Class 106 (1). Digital-data-processing apparatus includes a signal store divided into a plurality of information storage sections each associated with a marker signal storage section, means for scanning the storage sections in a predetermined sequence, and means for reading out selected information. Each track 3 of a magnetic drum store 1 stores details of a customer's account including a nett balance which may be compared with a standard debit amount stored in a track 38. All debit balances exceeding this amount are marked in a section 5 of the drum, and subsequently, a rapid scan of this section allows for quick compilation of a list of such balances. Thus, there are two routines:-a test routine during which accounts are examined in succession and each balance is tested against the standard; and a select routine during which only those accounts which have been marked are printed out. The test routine is initiated by closing a switch 18 which allows an end of revolution pulse 14, picked up by a head 12, to set a TEST flip-flop 20 ; this opens a gate 22 which allows subsequent pulses from the head 12 to operate a counter 7, 8 which influences a selector 6 to select track heads 4 in succession. 496 heads 4 are arranged in sixteen groups of thirty-one heads each, and while the output leads of the counter section 7 are connected in parallel to each group of heads, the counter section 8 selects the groups in turn each time the section 7 completes a cycle. At the beginning of each drum rotation a flip-flop 33 is set by the end of revolution pulse 14 and, thereafter, clock pulses from a track 11 are fed through a gate 34, opened by the flip-flop 33, to step on a 32-stage counter 32. The output pulse from this counter (which defines the extent of the marker section of the drum) resets the flip-flop 33 and sets another flip-flop 29 which allows information such as customer's balance, picked up by the selected head 4, to pass via an amplifier 24 and gates 26, 54 to an arithmetic unit 37 at the same time as the standard debit amount read from the track 38 passes via gates 41, 42 to the arithmetic unit. If the latter finds that the customer's debit balance exceeds the allowable figure an output signal sets a flip-flop 44 to initiate the marking procedure. A pulse 17 picked up at the end of the " balance " section of the track, causes the flip-flop 29 to be reset. The flip-flop 44 closes a gate 23 to prevent the next pulse 14 from reaching the counter 7, but clock pulses reach the counter 32, as before, stepping it on until, when it registers the same count as the counter 7, a comparing circuit 45 passes a clock pulse through via a gate 46 to record a mark on the selected track at a position corresponding with the number of that track within its group. When the counter 32 completes its cycle the output pulse resets the flip-flop 44 which then supplies a pulse to the counter 7 in substitution for the one suppressed, thus avoiding an inactive revolution of the drum. In this manner all the tracks are systematically tested and marked where necessary before an output pulse from the counter 8 resets the TEST flip-flop 20. The Select routine is initiated by closing a switch 49 which allows the next pulse 14 to set the SELECT flip-flop 31 ; this opens a gate 50 to allow the higher-frequency clock pulses from track 11 to step on the counter. Thus the heads 4 of one group scan across the section 5 of the drum during a fraction of a rotation until a mark is detected. This generates a pulse which passes via amplifier 24 and gates 25 to 27 to set a flip-flop 28 which shuts the gate 51 to suppress the supply of clock pulses to the counter 7 and opens a gate 56 to allow the output pulse from the counter 32 to set the flip-flop 29 and so open gate 26 which allows information regarding the marked customer's account to be passed via an open gate 57 to output means 55. At the end of this drum rotation the supply of clock pulses to the counter 7 is not resumed until the counter 32 reaches the same registration, as detected by the comparing device 45. The scanning process is then resumed until the next mark is detected, and so on. Various modifications are suggested: e.g. there may be several information areas, with associated marking areas, to each track; there may be several drums mounted on a common shaft or geared together, and movable heads or groups of heads may be used. Other forms of storage such as magnetic core matrices, magnetic tape loops or discs could be used. Specifications 818,623 and 827,163 are referred to.